Good tips for iphone application developers before beginning

Guide for a developer before designing an application:

http://developer.apple.com/library/ios/#referencelibrary/GettingStarted/Creating_an_iPhone_App/index.html

useful tips on why apple banned competing Ad's from its platform:

http://www.iphonedevelopmenttalk.com/2010/06/11/why-apple-banned-competing-ads-from-its-platform/